Slide rule



April 1, 1958 J. MONDRY SLIDE RULE Filed Nov. 13, 1956 1NVENTOR.

2,82,9l5 Patented Apr. 1, 1958 LIIDE RULE lion Mondry, Detroit, Mich.

Application November 13, 1956, Seriai No. 621M253 9 Claims. (Cl. 2-35-30) This invention relates generally to computing devices and more particularly to a direct reading adding and subtracting slide rule.

An object of this invention is to provide an improved slide rule.

Another object of this invention is to provide a slide rule which is operable in adding or subtracting to indicate the final answer directly without requiring any interpolation.

A further object of this invention is to provide a slide rule in which a mechanical counter is operated by the usual slide rule runner movement, for operation of the slide rule to indicate a final computation answer directly on the counter.

Still a further object of this invention is to provide a slide rule which is simple in construction, economical to manufacture and elhcient in operation in indicating directly the result of an adding and/or subtracting operation.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description when taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevational view of the slide rule of this invention with some parts broken away to better illustrate the slide rule construction;

Fig. 2 is an enlarged fragmentary side elevational view of a portion of the slide rule illustrated in Fig. 1;

Fig. 3 is a transverse sectional view looking along the line 33 in Fig. 1;

Fig. 4 is an end view of the slide rule of this invention, with some parts broken away and other parts shown in section for the purpose of clarity; and

Fig. 5 is a detail view of one end of the runner in the slide rule of this invention.

With reference to the drawing, the slide rule of this invention, indicated generally at id, is illustrated in Fig. 1 as including a body member 11 having a pair of trans versely spaced portions 12 and 13 connected at their ends by straps M. A longitudinally extended slide member id positioned between the body member portions 12 and 13, has a pair of oppositely extended tongues 17 (Fig. 4) received in corresponding grooves 18 formed in the body member portions 12 and 13 to provide for a slidable support of the slide member 16 on the body member lit. The body member portion 12 and the adjacent side of the slide member in are provided with matching X and Y scales l9 and 22., respectively, illustrated as extending from 0 to 30 and calibrated in tenths between adjacent numbers. Likewise, the opposite side of the slide member lie and the body member portion 13 are provided with matching U and V scales 22 and 23 illustrated as extending from to 100. A shaft 24 provided with a plurality of spiral grooves 26 extends longitudinally of and is positioned within the body member portion 112. A similar shaft 27, likewise provided with a plurality of parallel spiral grooves 28 of a smaller pitch than the groove 26 extends longitudinally of and is positioned within the body member portion 13.

The shafts 24 and 27 are connected for concurrent rotation by a belt 29 (Figs. 1 and 3) extended about the shafts 24 and 27 at a position to the left of the slide member 16 as viewed in Fig. 1. A mechanical counter 31 (Fig. l) is connected directly to the shaft 24 for operation in response to rotation of the shaft 24 and has manually operable disks 32 for returning the counter 31 to Zero.

A runner 33 (Figs. 1, 2 and 4) slidably mounted on the body member ll has the usual transparent viewing side 3d provided with a hair line 36 positioned opposite the side of the body member ll provided with the X, Y, U and V scales. At its transversely opposite ends, the runner 33 supports a pair of pins 37 and 38 corresponding to the shafts 24 and 27, respectively, and extended inwardly of the body member 11 through slots and in the body member portions 12 and 13, respectively, for engagement with the shafts 24 and 27. Each of the pins 3'7 and 38 has a head 4-2 provided with an inclined surface 43. A spring 44 is positioned about each of the pins 37 and 38 and extends between and is secured to a corresponding pin head 42 and the runner 33 for biasing the pins 37 and 38 out of engagement with the corresponding shafts 24- and 27.

Associated with each of the pins 37 and 38 is a locking plate 56 mounted on an adjacent end of the runner 33 for locking a pin or 38 in a position in engagement with the corresponding shaft 24 or 27. Each plate 46 has a slot 47 through which a pair of screws 48 carried by the runner 33 are extended to provide for sliding movement of the plate 46 toward and away from the head 52 of a corresponding pin 37 or 38.

On movement of a plate 46 toward the corresponding pin head d2, the end 49 of the plate 46 engages the inclined head surface 43. As a result, on continued movement of the plate 46, the pin 37 or 38 is moved toward the corresponding shaft 24 or 27, respectively, to a final position in which the plate 46 overlies the head 42 and locks the pin 37 or 38 in a shaft engaging position in which the pin extends into the shaft groove 26 or 28. Such a position is illustrated for the pin 37 in Pig. 1. On sliding movement of a locking plate as in an opposite direction to a position in which the end 49 thereof is in a clearance relation with the corresponding pin head 52, the spring 3 provides for an automatic disengagement of the pin 37 or 38 from the corresponding shaft 24 or 2.7, respectively.

it is seen, therefore, that on sliding movement of the runner 33, with the pin 37 received in a groove 26 for the shaft 24, the shaft 24 is rotated. On movement of the runner toward the right, as viewed in Fig. 1, the numbers on the counter 31 are progressively advanced in response to rotation of the shaft 24. Conversely, on movement of the runner 33 toward the left, as viewed in Fig. l, the numbers on the counter 31 are progressively retracted. By virtue of the assembly of the belt 29 with the shafts 2d and 2'7, movement of the runner 33 with the pin 38 received in a groove 28 in the shaft 27 has a similar effect on the counter 31.

The counter 31 is initially assembled in the slide rule Ml such that on movement of the runner 33 from a position in which the hair line 36 is on zero for the X scale, and the pin 37 is engaged with the shaft 24, to a position in which the hair line 36 is at a position on the X scale indicated on the scale by the numeral 1, the shaft 24 is rotated an amount necessary to provide for a 10 advancement of the counter 31. Similarly, the pitch of the grooves 28 on the shaft 27 is such that on movement of the runner from 0 to 10 on the U and V scales, with the pin 38 held in the groove 28, the shaft 24 is rotated an amount necessary to provide for a 1 advancement of the counter 31. When the runner movement is in the opposite direction, namely, to the left in Fig. l, the indicated number on the counter 31 is retracted a similar amount. The slide member 16 is used in the usual slide rule manner to measure the desired movement of the runner 33 with the Y and U scales.

By virtue of the dilferent pitches of the grooves 2x6 and 28 in the event both pins 37 and are engaged with the corresponding grooves 26 and 28, respectively, which event never occurs intentionally in normal operation of the slide rule lo, the runner 33 is locked. Such locking positively prevents accidental rotation of both the shafts 24- and J at the same time.

in the operation of the slide rule a range of either -300 or (l-3000 may be assigned to the XY scales. In other words, when the XY scales are assigned a range of t)-30() the numeral 1 on each scale represents on the counter 31. When a range of 0-3080 is assigned, the numeral 1 on the XY scales represents lOti on the counter in both cases the counter 31 reads 10 but in the first case this reading repre ents 1G and in the second case the reading represents 100.

The narrow range of 0-300 is normally used when a column of two and three digit numbers less than 300 are involvet. There is more chance of going off scale when the narrow range is used but to bring the runner 33 back on scale it is only necessary to utilize a finger motion to retract the pin 37 and manually return the runner 33 to a zero position at which time the pin 37 is re-engaged with the shaft 24 at a groove 26 and the operation is continued. In the earlier adding and subtracting slide rules which have come to my attention it has been ditlicult to bring the runner back on scale after the calculation has extended past the right hand end of the rule. in most cases, a mental or written calculation has been required.

The advantage of a narrow range assignment to the scales is that the final calculation is read directly on counter and no use of the UV scales is required. a calculation in which the wider 0-3000 range is signed, the UV scales are used and the units place in the answer is read from the V scale.

As an example of the operation of the slide rule 10, assume that the numbers 204, 37 and 851 are to be added and the numeral 699 subtracted from the added total. To illustrate the use of all the scales let us further assume that a 030C0 range is assigned to the XY scales. The counter disks are manually manipulated to provide for a zero indication on the counter 31. The locking plate 4-6 are moved to positions in a clearance relation with the pin heads so that both pins and 38 are retracted by their corresponding springs the runner is moved to a position in which hair line 3-3 is on zero for the X scale. The locking plate for the pin is then manipulated to lock the pin 37 in a position received in a groove 26, being sure at the plate for the pin 33 remains in a clearance rotation with the pin By manipulating the slide months i, the runner 33 is progressively moved toward the ht in 3 to add the numerals 200, and "859, so that the hairline 36 is opposite 1080 on the X scale. in response to such movement of the runner 33, the shaft 24 is rotated to provide for the numeral 08 on the counter 31. The numeral 690 is then subtracted by manipulating the slide member 16 so that 690 on the Y scale is positioned opposite the hairline 36, after which the runner 33 is moved to the left as viewed in Fig. l to a position in which the hairline 36 is opposite zero on the Y scale. In response to such movement, the counter 31 is retracted so that the numeral 39 is indicated thereon.

Thus far, only the tenths and hundredths places in the the locking plate as for the is moved to a position in which the pin 38 is moved into a groove 23. The

slide member is then manipulated in the usual manner so scale is utilized with the runner 33 and the scale to add the numerals 4, 7 and l and subtract the numeral 9. A; the end of such manipulation,

the hairline 36 is opposite the numeral 3 for the V scale and th total on the counter I'll has not been changed.

nal reading, representing the result of the above nation, therefore, is 393. if the units place calion had been such that the hairline 3d finally rested 13 instead of 3 the counter would have been advanced by to show a final figure of 40 and the answer would, therefore, be 4-03. Thus the last digit in the final V scale reading represents the units place in the final answer. in the last example the 1S portion of the 13 was registered on the counter by the belt 2% so that only the 3 portion is regarded in the final answer.

To solve the above problem by assigning a range of 0-360 to the XY scales, first manually set 851 on the counter 31 by manipulating the disks 3?... Add 204 and 37 in the usual way so that the counter 3-1 reads i092 and the runner hairline 36 is on 241 on the X scale. Manually subtract 600 on the counter 31 by manipulating the two appropriate disks so that the counter then reads 492. The 99 remainder from 699 is then subtracted by manipulating the X and 'i scales in the usual way so that the final answer 393 is read on the counter 31.

From the above description it is seen that the slide rule 71% of this invention combines the usual slide rule body 11 and slide member If with the mechanical counter which is operated in response to travel of the runner 33 for indicating the result of an adding and/ or subtracting operation directly on the counter Pill. The answer ei her appears completely on the counter or on the counter and the V scale together. Since the hairline 36 is at all times aligned with the calibration lines of either the X and Y or U and V scales, no interpolation is required in the use of the slide rule ill. As a result, a

ole .nd accurate answer is always obtainable. By the assembly of the slide rule 10 in a form lly expected of a slide rule, it is conveniently combined with the usual slide rule scales for multiplying, dividing, etc, by forming the X, Y, and V sca es for adding and subtracting on one side of a slide rule body, having the usual multiplying, dividing, etc. scales on the other side. The runner is readily brought back on scale by virtue of the coaction of the pins 37 and 3-3 and the shafts Z l and 27. urthermore, an infinite list of numbers can added or subtracted with the slide rule the only limitation being the capacity of the counter The multi-groove character of the shafts 2 5' and a: insures an engagement of a pin 37 or 33 with a groove 26 or 2 5-, respectively, at any position of the runner 33.

Although the invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited, since changes can be made therein which are within the scope of the invention as defined by the appended claims.

What is claimed is:

l. A direct reading adding and subtracting slide rule comprising a pair of interfitting members arranged for relative movement and provided with matching scales, a runner slidably mounted on said members, a counter mounted on one of said members, and means on said one member connected to said counter for operating the counter in response to movement of said runner longitudi nally of said one member in amounts measured by said scales.

2. A direct reading adding and subtracting slide rule comprising a pair of elongated interfitting members arranged for relative longitudinal movement, a runner slidably mounted on said members, a counter mounted on one of said members, a shaft mounted on said one member and connected to said counter for operating the counter in response to rotation of said shaft, and coacting means on said shaft and said runner providing for rotation of said shaft in response to movement of said runner longitudinally of said members, with said rotation being in a predetermined relation to movement of said runner as measured by said scales.

3. A direct reading adding and subtracting slide rule comprising a pair of elongated interfitting members arranged for relative longitudinal movement, a runner slidably mounted on said members, a counter mounted on one of said members, a shaft on said one member connected to said counter for operating the counter in response to rotation of said shaft, and coacting pin and groove means on said shaft and said runner providing for rotation of said shaft on movement of said runner longitudinally of said one member.

4. A direct reading adding and subtracting slide rule comprising a longitudinally extended body member having a pair of transversely spaced portions provided with scales, a slide member slidably mounted on said body member for movement longitudinally there of between said portions, said slide member having a pair of scales thereon corresponding to and positioned opposite the scales on said body member, a pair of shafts extended longitudinally through said body member portions, a runner slidably mounted on said body member, a counter mounted on said body member and operatively associated with said shafts for operation in response to rotation thereof, and coacting means on said runner and said shafts providing for rotation of said shafts in predetermined amounts in response to movement of said runner measured distances longitudinally of said body member.

5. A direct reading adding and subtracting slide rule comprising a longitudinally extended body member having a pair of transversely spaced portions provided with scales, a slide member slidably mounted on said body member for movement longitudinally thereof between said portions, said slide member having a pair of scales thereon corresponding to and positioned opposite the scales on said body member, a pair of shafts extended longitudinally through said body member portions, a runner slidably mounted on said body member, a counter mounted on said body member and connected directly to one of said shafts for operation in response to rotation thereof, means extended between said shafts providing for concurrent rotation thereof and coacting pin means on said runner and spiral groove means on said shafts providing for rotation of said shafts in response to movement of said runner longitudinally of said body member.

6. A direct reading adding and subtracting slide rule comprising a longitudinally extended body member having a pair of transversely spaced portions provided with scales, a slide member slidably mounted on said body member for movement longitudinally thereof between said portions, said slide member having a pair of scales thereon corresponding to and positioned opposite the scales on said body member, a pair of shafts extended longitudinally through said body member portions, a runner slidably mounted on said body member and provided with a pair of pin members corresponding to said shafts, each pin member being mounted for movement into engagement with a corresponding one of said shafts, with each of said shafts having multi-spiral grooves formed thereon for receivinga pin member to provide for rotation of a shaft in response to sliding movement of said runner with a pin member thereon received in a groove for said shaft, with each of said multi-spiral grooves being formed to provide for rotation of the shaft therefor in a predetermined measured relation with the scale corresponding thereto, and a counter mounted on said body member and operatively associated with said shafts for operation in response to rotation thereof.

7. A direct reading adding and subtracting slide rule comprising a body member, a shaft mounted on said body member and provided with spiral groove means, a runner mounted for sliding movement on said body member, a pin member carried by said runner for selective reception in said groove means to provide for rotation of said shaft on sliding movement of said runner with said pin member received in said groove means, a numbered slide member mounted for sliding movement on said body member for measuring said runner movement, and counter means connected to said shaft for operation in response to shaft rotation for visually indicating the movement of said runner in numbers related to said scale.

8. A direct reading adding and subtracting slide rule comprising a body member, a counter mounted on said body member, a first shaft on said body member connected directly to said counter to provide for operation of the counter in response to rotation of said shaft, a second shaft on said body member, means connected to and extended between said shafts providing for rotation of said first shaft in response to rotation of said second shaft, a slide member having a pair of scales thereon corresponding to said shafts and slidably mounted on said body member, a runner slidably mounted on said body member, and coacting means on said runner and said shafts providing for selective rotation of said shafts in response to sliding movement of said runner, with rotation of a shaft being in a predetermined proportional relation with the scale corresponding thereto.

9. A direct reading adding and subtracting slide rule comprising a body member provided with a numbered scale, a shaft mounted on said body member and pro- No references cited. 

